Might I suggest looking at https://sourcegraph.com? Currently it's just code search, and doesn't do code review. But it does understand the code at a function/class/module level. And that makes it fundamentally different from a lot of other code reading tools out there that just treat code as text. For code search, that means it can do things like show you how other people actually call a given function. For code review, it would make it possible to reason about changes to functions/classes/packages instead of lines of text. (Disclaimer: I'm one of the creators of Sourcegraph; would love to hear your feedback)